1. Field of the Invention
The present invention relates to an air conditioning assembly for cooling.
2. Description of the Prior Art
Most automotive air conditioning assemblies comprise a compressor, a gas cooler, an expansion device, and an evaporator. Conventional refrigerants include R 134a and R 744 (Carbon Dioxide). The air conditioning assemblies that utilize R 134a as the refrigerant typically operate such that the critical pressure of the refrigerant is not exceeded. Heat supply and heat removal take place via evaporation and condensation of the refrigerant and there is no need for an internal heat exchanger.
However, in the air conditioning assemblies that utilize R 744 as the refrigerant, the pressure of the refrigerant in the system may become higher than the critical pressure of the refrigerant. Under this condition, the fluid exiting the gas cooler remains a high pressure, high temperature vapor. Also, the vapor exiting the evaporator contains a fraction of low pressure, low temperature residual liquid. The cooling of the high temperature, high pressure gas with the low temperature fluid exiting the evaporator improves the efficiency level of the assembly. To obtain an efficiency level equal to or better than an assembly utilizing R 134a as a refrigerant, it is necessary to use a heat exchanger in fluid communication with the gas cooler, the expansion device and the evaporator.
Typically, the gas cooler is located in the front of the vehicle and the compressor is located away from the gas cooler and closer to the evaporator. These physical restrictions make it impractical to use a heat exchanger without compromising the overall performance of the air conditioning assembly. As such, when there is a need for an internal heat exchanger, the internal heat exchanger is often manufactured and installed separately. Such an internal heat exchanger may be a suction line heat exchanger, which cools the fluid leaving the condenser (in a traditional refrigerant system) or the gas cooler (in an R 744 system). In an R 744 system, when an accumulator/dehydrator is placed at the front of the vehicle for packaging purposes, a suction line has to be routed to the front of the vehicle. In such cases, the most beneficial location of the internal heat exchanger is near the gas cooler at the front of the vehicle. The combination of the separate installation of the heat exchanger and the positioning of the heat exchanger at the front of the vehicle results in increased assembly costs and additional connection equipment.
The U.S. Pat. No. 5,544,498 to Benedict discloses an air conditioning assembly including a compressor, a gas cooler, an expansion device, an evaporator, and a heat exchanger. The heat exchanger is used to remove residual vapor from liquid refrigerant and residual liquid from vapor refrigerant as the refrigerant circulates through the system. The U.S. Pat. No. 6,189,334 to Dienhart, et al. provides for a similar air conditioning assembly with the heat exchanger and the gas cooler in one constructional unit.
Although the prior art connects a heat exchanger to a gas cooler in an air conditioning system, the heat exchanger and the gas cooler are separately constructed and fabricated, i.e., the heat exchanger is essentially a separate component to the gas cooler.